Most MCUs apart from Cortex-M0 with Thumb 1 have an instruction
for computing the "high part" of a multiplication (e.g., the upper
32 bits of a 32x32 multiply).
When they do, gcc uses this to implement a small and fast
overflow check using the __builtin_mul_overflow intrinsic, which
is preferable to the guard division method previously used in smallint.c.
However, in contrast to the previous mp_small_int_mul_overflow
routine, which checks that the result fits not only within mp_int_t
but is SMALL_INT_FITS(), __builtin_mul_overflow only checks for
overflow of the C type. As a result, a slight change in the code
flow is needed for MP_BINARY_OP_MULTIPLY.
Other sites using mp_small_int_mul_overflow already had the
result value flow through to a SMALL_INT_FITS check so they didn't
need any additional changes.
Do similarly for the _ll and _ull multiply overflows checks.
Signed-off-by: Jeff Epler <jepler@gmail.com>
Makes it compatible with the __builtin_mul_overflow() syntax, used in
follow-up commit.
Includes optimisation in runtime.c to minimise the code size impact from
additional param.
Signed-off-by: Damien George <damien@micropython.org>
Signed-off-by: Angus Gratton <angus@redyak.com.au>
Blanket wide to all .c and .h files. Some files originating from ST are
difficult to deal with (license wise) so it was left out of those.
Also merged modpyb.h, modos.h, modstm.h and modtime.h in stmhal/.
